Beyond the Penrose Hypothesis: Examining the Association between the Availability of Psychiatric Care and National Homicide Rates in 166 Countries

Round 1

Reviewer 1 Report

Nicely done.  I did a quick check of the literature for this review and found articles on psychiatric care while incarcerated, including psychiatric care for inmates with specific mental conditions, and other studies of mental illness among convicted criminals, but none that looked at the association between the availability of psychiatric care and homicide rates.  I did however find some articles on the Penrose hypothesis: 

see 

Author Response

I thank the reviewer for their kind and insightful critique of the initial version of this manuscript.

I have made the following corrections / changes in response to their specific comments, as follows:

Comment 1. "I did a quick check of the literature for this review and found articles on psychiatric care while incarcerated, including psychiatric care for inmates with specific mental conditions, and other studies of mental illness among convicted criminals, but none that looked at the association between the availability of psychiatric care and homicide rates.  I did however find some articles on the Penrose hypothesis: 

see 

Toynbee M The Penrose hypothesis in the 21st century: revisiting the asylum  Evidence-Based Mental Health 2015;18:76.     

O’Neill, C. J ; Kelly, B. D ; Kennedy, H. G.  "A 25 year dynamic ecological analysis of psychiatric hospital admissions and prison commitments:  Penrose hypothesis updated "  Irish journal of psychological medicine, 2021, Vol.38 (3), p.182-185   

Mundt, & Konrad, N. (2019). Institutionalization, Deinstitutionalization, and the Penrose Hypothesis. In Advances in Psychiatry (pp. 187–196). Springer International Publishing. https://doi.org/10.1007/978-3-319-70554-5_12   

You might want to consider reading/referencing these before publication of your article."

Response: I agree with these suggestions and apologize for the omission of these papers from the original manuscript. They have been cited (references no. 18, 21 and 24) in the revised manuscript and discussed in the text as follows:

Introduction:

"Studies from the United Kingdom [17], Ireland [18] and Hungary [16] have all reported significant negative correlations between the number of psychiatric beds and the prison population; in all these countries, a reduction in the number of psychiatric beds was associated with an increase in the prison population over time, though no definitive conclusion regarding causality could be drawn from this data."

"A subsequent critical appraisal of the above two studies noted that these associations needed to be replicated in further longitudinal studies, and also highlighted the importance of correcting for potential confounding factors, such as government spending on health and the level of urbanization [21]."

"A subsequent critical appraisal of the above two studies noted that these associations needed to be replicated in further longitudinal studies, and also highlighted the importance of correcting for potential confounding factors, such as government spending on health and the level of urbanization [21]."

Discussion:

"Th[e above findings] suggests tha the hypothesis advanced by Mundt and Konrad regarding the geographically and temporally restricted nature of the “Penrose effect” merits further consideration [24]." (This is elaborated further in the response to the second review comment, below).

Comment 2.  "I would also like to have seen more detailed discussion of the applicability of the Penrose hypothesis to different regions.  Perhaps also some discussion of its applicability/usefulness as it applies to different regions within the same country:  national data often hides internal regional differences.  large nations are not uniform entities."

Response: I agree with the reviewer that this discussion was lacking in the original manuscript. The following changes have been made in the Discussion:

"It is possible that the “Penrose effect”, as initially described, is of relevance only to higher-income countries during a period characterized by a greater availability of psychiatric institutional beds [25-29], and may have limited or no applicability following the process of deinstitutionalization, or in countries where the institutionalization of patients with mental illness was never widespread to begin with [27].The positive correlation between indices of psychiatric care and prison populations in low- and middle-income countries is counter-intuitive and requires further exploration; possible explanations include cultural and economic factors influencing rates of offending, higher levels of stigmatization of mental illness that may delay or prevent appropriate treatment, differences in legislation pertaining both to incarceration and to psychiatric admission, and differences in governmental priorities and investment in the criminal justice and mental health systems [14, 30, 78-80]. Alternately, this association may reflect a process of cultural change and transition, characterized by a gradual increase in investment in mental health in these countries; if this is the case, the aforementioned association would not remain stable over time, and might even decline as psychiatric care becomes more widely available and accessible [81, 82]. Changes in the political landscape can also influence the balance between mental health care and incarceration of mentally ill offenders, as can be inferred from cases of countries where a shift towards a more authoritarian form of government was associated with reduced support for rehabilitation of the mentally ill [83].

It is also important to note that the analysis of country-level data can obscure important differences between regions of the same country. For example, rates of both psychiatric hospitalization and incarceration were found to vary significantly across different states of the United States of America, probably reflecting differences in local culture and demographics as well as state government policy [84]. Likewise, the marked divide between the availability of mental health in rural and urban regions, particularly in low- and middle-income countries [85], could lead to significant variations in any observed relationship between psychiatric care and homicide when these regions are compared. Similar considerations should be kept in mind when considering specific populations within the same country, particularly ethnic minorities or migrants who are likely to receive a sub-optimal level of mental health care [86, 87] and may experience a certain degree of bias or discrimination in encounters with the legal system [88]."

Reviewer 2 Report

1. A large part of the studies included in the first part of the article refers to the relationship between the number of beds in psychiatric hospitals and prison population. Or in prisons there are people who have committed many types of crimes (rape, sexual assault, pedophilia, drug trafficking, theft, etc.). The studies discussed should highlight the relationship between mental illnesses and homicides.

2. The article also discusses violent crimes and the relationship with psychiatry. The discussion should be focused on homicides because the violent crimes also includes other types of acts of violence with a variety of risk factors (for example, violent crimes include rape, robbery, murder, attempted murder, injuries causing death, sexual assaults).

3. The author uses the term "Female homicide rate". What is the definition of this rate? Is femicide rate=number of female killed /100.000?

4. Male homicide rate is number of men killed/100.000?

5. I recommend the authors to read the report of the World Health Organization from 2002 (Krug et al, 2002, World report on violence and health https://books.google.ro/books?printsec=frontcover&vid=ISBN9241545615&redir_esc=y#v=onepage&q&f=false ), in which the specific risk factors for homicidal respondents were described from the perspective of the ecological model (individual, relational, community, societal factors) and possibly to introduce in the analysis other indicators referring to the countries included in the analysis (arms regime, alchool consumption etc).

Author Response

I thank the reviewer for their thoughtful and in-depth critique of my original manuscript.

I have made corrections and provided clarifications in the revised manuscript as follows:

Comments 1 and 2. "1. A large part of the studies included in the first part of the article refers to the relationship between the number of beds in psychiatric hospitals and prison population. Or in prisons there are people who have committed many types of crimes (rape, sexual assault, pedophilia, drug trafficking, theft, etc.). The studies discussed should highlight the relationship between mental illnesses and homicides.

2. The article also discusses violent crimes and the relationship with psychiatry. The discussion should be focused on homicides because the violent crimes also includes other types of acts of violence with a variety of risk factors (for example, violent crimes include rape, robbery, murder, attempted murder, injuries causing death, sexual assaults)."

Response: I agree with the reviewer's comments. The references to studies related to other violent crimes have been shortened and confined to a single sentence in the Introduction. References to recent studies on homicide and mental illness have been added to the Introduction (references no. 10, 11, 12) and discussed in the text as follows:

"Rates of psychiatric diagnoses in individuals convicted of homicide have been found to vary significantly across studies. For example, a survey of individuals convicted of homicide in the United Kingdom found that 34% met criteria for a mental disorder [7]. On the other hand, a similar study of homicide offenders from Sweden found that 90% fulfilled the diagnostic criteria for at least one psychiatric disorder [8]. In this context, it is important to distinguish between the presence of a psychiatric diagnosis, which is made according to standard criteria developed by health professionals, and the determination of criminal responsibility for homicide, which is a legal judgement. In the study from the United Kingdom referenced above, only 9% of perpetrators received a verdict of “diminished responsibility” on the basis of their psychiatric diagnosis [7]; likewise, in a study of adult homicide perpetrators in Ontario, Canada, less than 4% of individuals were classified as “mentally abnormal homicides” requiring psychiatric treatment [9]. An analysis of data from New South Wales, Australia found that less than 8% (169 of 2159) of homicide offenders brought to trial in the period 1993-2016 received a verdict of “not guilty on the grounds of mental illness”. The most common diagnosis in this subgroup was schizophrenia or a related psychotic disorder (89%). Most of these offenders had a history of prior contact with mental health services, but only half were receiving pharmacological treatment [10]. A study of 5741 persons facing charges of homicide in the Russian Federation found that only 3% received a diagnosis of schizophrenia. This study also found that rates of homicide related to schizophrenia rose and fell over the period 1981-2020, and this pattern paralleled time trends in homicides not related to schizophrenia, suggesting that social factors may have influenced the risk of homicide in both groups [11]. A similar analysis of time trends in homicide from the United Kingdom found that, while the overall homicide rate decreased in the period 1997-2015, the rate of homicide perpetrated by mentally ill offenders increased slightly, and highlighted the lack of appropriate treatment given to such offenders [12]. The overall picture emerging from this research is that of an increased risk of homicide in individuals with severe mental illness, particularly when associated with substance use, inadequate treatment, and social adversity."

Comments 3 and 4. 

3. The author uses the term "Female homicide rate". What is the definition of this rate?Is femicide rate=number of female killed /100.000?
4. Male homicide rate is number of men killed/100.000

Response: I apologize for the lack of clarity in the original version of the manuscript. This has been explained clearly in the revised manuscript as follows: "Male homicide rate was defined as the number of male homicide deaths per 100,000 male population, and female homicide rate was defined as the number of female homicide deaths per 100,000 female population." This has also been mentioned in Table 1.

Comment 5. "I recommend the authors to read the report of the World Health Organization from 2002 (Krug et al, 2002, World report on violence and health https://books.google.ro/books?printsec=frontcover&vid=ISBN9241545615&redir_esc=y#v=onepage&q&f=false ), in which the specific risk factors for homicidal respondents were described from the perspective of the ecological model (individual, relational, community, societal factors) and possibly to introduce in the analysis other indicators referring to the countries included in the analysis (arms regime, alchool consumption etc)."

Response: I agree completely with this suggestion by the reviewer. This book has been cited and discussed in the revised manuscript (reference no. 32):

Section 2.2: "Each act of violent crime does not result from a single causal factor, but it the result of an interaction between individual, interpersonal, social and environmental factors [32]."

"Finally, the availability of alcohol and firearms can also increase the risk of interpersonal violence and homicide at a regional or national level [32]; hence, these two variables were also included as potential confounding factors in the analysis."

These two additional variables (alcohol consumption per capita and rate of gun ownership) were also added to the analysis as discussed below:

Section 2.3: "Information on alcohol use (estimated as per capita alcohol consumption among the adult population) was obtained from the World Health Organization’s Global Health Observatory; the most recent values available, which were for the year 2016, were used in the analysis [41]. Information on firearm access (estimated as number of firearms per 1,000 population) was obtained from the University of Sydney’s Gun Policy database, which provides information on gun ownership for 206 countries and regions; the estimates used in this study were based on data for the year 2017 [45]."

Section 3: "Neither per capita alcohol consumption nor firearm access was significantly correlated with national homicide rates, either overall or when analyzed according to gender; however, both these variables were positively correlated with indices of psychiatric care." (Exact values are presented in the revised version of Table 3.)

"When per capita alcohol consumption and firearm ownership were also included as covariates, the results were unaltered; the number of general hospital psychiatric beds, but not psychiatrists, remained significantly and negatively correlated with all three homicide rates."

Reviewer 3 Report

There is an error in the placement of the maximum and minimum for last three entries of table 1?

Author Response

I thank the reviewer for their thoughtful review of my original manuscript.

I have made corrections to the revised manuscript as follows:

Comment 1. There is an error in the placement of the maximum and minimum for last three entries of table 1?

Response. I apologize for this error which occurred inadvertently during formatting of the tables. The correct maximum and minimum values have been inserted in the revised manuscript.

Round 2

Reviewer 2 Report

I have no other comments for the author.